1. Technical Field
The present inventions relate to chips which operate differently depending on where they are positioned in a system.
2. Background Art
Various arrangements for memory chips in a memory system have been proposed. For example, in a traditional synchronous dynamic random access memory (DRAM) system, memory chips communicate data through bidirectional data buses and receive commands and addresses through command and addresses buses. The memory chips have stubs that connect to the buses.
In other memory systems, a memory chip receives signals and repeats them to a next memory chip in a series of two or more memory chips. In some of these systems, the last memory chip in the series can send a signal directly back to a memory controller or other originating chip. This is referred to as a ring.
Memory modules include a substrate on which a number of memory chips are placed. The memory chips may be placed on only one side of the substrate or on both sides of the substrate. In some systems, a buffer is also placed on the substrate. For at least some signals, the buffer interfaces between the memory controller and the memory chips on the module. In such a buffered system, the memory controller can use different signaling (for example, frequency and voltage values, and point-to-point versus a multi-drop arrangement) with the buffer than the buffer uses with the memory chips. Some computer systems include wireless transmitter and receiver circuits.